Axial flow pumps



Aug. 19, 1958 w. M. JACKSON 'AXIAL FILow PUMPS Filed Nov. 2. 1953 INVENTOR ATTORNEYS United States Patent ()fiice xxur: stow-mm is.

William M. Jackson, Montgomery, Ala.

Application November 2, 1953, Serial No. 389,718 3 Claims. (Cl. 103-89) This invention relates to hydraulic pumps and more particularly to axial flow pumps.

It is the primary object of this invention to provide a pump which is compact in nature, light in weight, and which has the pumping capacity of much larger than bulkier pumps.

It is another object of the present invention to provide a pump in which the increased pumping capacity is accomplished by the shape of the pump housing adjacent the tips of the blades.

Another object of the invention is to provide a pump in which back flow pressure which is normally present in axial flow pumps is substantially eliminated.

A further object of the invention is to provide a pump having a shroud structure comprising two venturi sections lying adjacent each other and circumferentially disposed adjacent the path followed by the tips of the impeller blades to eliminate the aforementioned backflow pressure.

Other objects and advantages will be apparent from the following more detailed description of a preferred embodiment of the present invention read in connection with the accompanying drawings in which:

Fig. 1 is a view partly in side elevation and partly in vertical section showing the pump housing and an impeller positioned therein; and

Fig. 2 is a fragmentary similar view of a modification.

In order to facilitate an understanding of the present invention, reference is now made in more detail to the drawings. Reference numeral designates a fluid re action device or impeller comprising a hub 11 and a plurality of radially extending blades 12. The hub 11 of the impeller is mounted on a drive shaft 34 shown by dotted lines in Fig. l, by any suitable means such as a lock nut 13. Any suitable motor may be used to rotate the shaft and impeller, however, since the details of the drive mechanism form no part of the present invention, they are not illustrated herein.

The pump housing is made up of a generally cylindrical casing 14 into which a housing 15 extends, preferably on the inletside of the pump, to accommodate the drive mechanism. It is apparent that the position of the said mechanism is a matter of choice and that it could just as well be positioned on the outlet side of the pump. Casing 14 also has a circumferential opening 16 to accommodate the shroud structure 17 which will be described in detail later. Adjacent opening 16, the cylindrical casing 14 has inclined surfaces 18 and 19 for purposes hereinafter set out.

The shroud structure 17 comprises two venturi sections 20 and 21 having internally diverging convex surfaces. These venturi sections form a concavity 22 between them. The venturi sections 20 and 21 have externally extending annular flanges 23 and 24 which engage annular flanges 25 and 26 provided externally of the casing 14 adjacent opposite sides of opening 16. The shroud structure is rigidly held in place by means of a suitable connection such as bolts 27, 28 and nuts 29, 30 securing the respec- 2,847,941 Patented Aug. 19, 1958 "mm... or." n. on.

2 tivie flanges23; 24 of"tlie"slifoud structure to therespee ti'veflanges" 25; 26 brine ca iig." Iiiitliis way thesliioud structure is 'hel'dfirmlya'g'aiiis the'bd'gefi of th'iopen'ing 16in theca'singto' reventany leakage: I

In the eitibodimer'it'sliowifirf Figlfl impeller .10 -isso positioned that the center" lineslie "in" the plane i n. lwl1'ich the "venturi sections" 20"ai1d'21"meeti The widthof' the blades in this embodiment is such that the leading and trailing edges do not overlie the points 32 and 33 on the minimum diameters of the venturi sections 20 and 21 respectively. The length of the blades 12 of the impeller is less than half of the minimum diameter of the sections so that there is a small clearance between the blades and the shroud structure. The impeller thus acts within the shroud structure to pump the fluid through the dual restricted area from left to right as viewed in Figure 1.

The venturi section 20 acts on the intake side of the pump while the venturi section 21 acts on the discharge side of the pump to prevent backflow around the tips of the impeller blades. It can readily be seen that the flow of fluid is brought into contact with venturi section 20 on the intake side at a point of greater diameter than the internal diameter of casing 14, due to the tapering portion 18 of the casing and the flow of fluid follows the curve of venturi section 21 on the discharge side to a like point due to the taper of portion 19 of the casing. Advantage is thus taken of the greatest possible length of the surfaces of the venturi sections.

Figure 2 illustrates a modification of the pump of the instant invention showing the impeller mounted with its center line further to the outlet side of the pump with the blades 12 of the impeller positioned so that edges extend axially to a point beyond the minimum diameter 33' of the venturi section 21 on the outlet side of the pump. Experiment has shown that the efliciency of the pump is not substantially affected with the blades positioned as in Fig. 2 or, on the other hand, with the blades positioned so that their trailing edges extend axially beyond the point of minimum diameter of the venturi section on the inlet side of the pump.

The axial flow pump illustrated and described above is by way of example only, and any changes which might occur to one skilled in the art are contemplated by the present invention, within the scope of the following claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In an axial flow pump, a shroud structure having two axially juxtaposed annular inwardly directed convex surfaces comprising venturi sections having a common axis, said surfaces defining between their loci of minimum diameter an annular depression of shallow generally V- shaped cross-section, and a propeller rotatably mounted within said shroud section, said propeller having radially extending blades, said blades having a center line normal to the propeller axis, said center line being located between the points of minimum diameter of said venturi sections, said propeller blades having a diameter less than the minimum diameter of said surfaces.

2. An axial flow pump as in claim 1 wherein the center line of the propeller blades coincides with a transverse plane through the locus of maximum diameter of said depression.

3. In an axial flow pump, a shroud structure having co-terminous annular surfaces of inwardly directed arcuate cross-section comprising venturi sections having a common axis and a propeller having blades of lesser diameter than said minimum diameter and mounted for rotation within said shroud structure, said blades having a center line located between the points of minimum diameter of said venturi sections.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS 4 Slocum Sept. 3, 1935 Adams Feb. 11, 1936 Bauer Aug. 14, 1945 McElroy Jan. 17, 1950 FOREIGN PATENTS Great Britain of 1867 Norway May 18, 1932 Great Britain Jan. 9, 1930 iArihu 

